This invention relates to herbicidal compositions and methods for their use.
Many derivatives of 2-chloroacetamide have hitherto been synthesized and among them, several derivatives, for instance, N-benzyl-2-chloroacetamide (refer to U.S. Pat. No. 2,864,679) and N,N-diallyl-2-chloroacetamide (refer to U.S. Pat. No. 2,864,683), have been known to exhibit herbicidal activity. However, the hitherto known derivatives of 2-chloroacetamide have demerits of their insufficient effect of herbicidal action, their lack of selectivity in only controlling noxious plants or weeds and their irritating action on human skin when applied.
The present inventors, as a result of studying the herbicidal action of derivatives of 2-chloroacetamide, have found that the compounds represented by the formula ##STR2## wherein R represents a methoxy, ethoxy, propoxy, isopropoxy or allyloxy have excellent herbicidal properties.
It is an object of this invention to provide a herbicidal composition comprising a herbicidally effective amount of a compound of the formula ##STR3## wherein R is methoxy, ethoxy, propoxy, isopropoxy or allyloxy and an agriculturally acceptable carrier.
A further object of this invention is to provide a method for inhibiting growth of weeds comprising applying a herbicidally effective amount of a compound of the formula ##STR4## wherein R is methoxy, ethoxy, propoxy, isopropoxy or allyloxy to soil medium to be inhibited said growth of weeds.
When applied to the fields of broad leaf crops such as cotton plants and soybean plants or the fields of other crop plants such as rice, wheat, barley and maize, these compounds exhibit excellent herbicidal activity to the graminaceous noxious weeds such as Digitaria sanguinalis (L.) Scopoli, Setaria viridis (L.) P. Beauv. var. minor, Poa annua L., Echinochloa Crus-galli P. Beauv. var. hispidula Honda, Echinochloa Crus-galli P. Beauve. and the likes, and to the portulacaceous noxious weeds such as Portulaca oleracea L. before germination or in the early stage of sprouting of the weeds into the soil of the fields.
The range of application of the compound as a component of the herbicidal composition includes the crop fields, the flooded paddy fields, orchards and non-arable fields such as play grounds and sites for factories and the like.
In addition, as a specific property of the compounds according to this invention, they do not show the irritative action to human skin in the cases where the human skin comes in contact with the compound when it is applied.
The compounds represented by the formula (I) are available by a public known process in which alkoxybenzene or allyloxybenzene is chloromethylated to chloromethylalkoxybenzene or chloromethyl-allyloxybenzene, and the thus obtained intermediate is subjected to amination to alkoxybenzylamine or allyloxybenzylamine, followed by the reaction of the aminated compound with chloroacetyl chloride. However, according to the studies of the present inventors, it has been found that the compound can be obtained simply in a high yield by amidomethylation of alkoxybenzene or allyloxybenzene with N-hydroxymethyl-2-chloroacetamide.
The concrete examples of the compounds represented by the general formula (I) and their respective structural formula are shown in Table 1.
TABLE 1 __________________________________________________________________________ Number of Structural formula of the compound compound Name of the compound Melting point (.degree.C.) __________________________________________________________________________ ##STR5## N(2-methoxyphenyl- methyl)-2- chloroacetamide 72-74.5 2 ##STR6## N(3-methoxyphenyl- methyl)-2- chloroacetamide 78-80 3 ##STR7## N(4-methoxyphenyl- methyl)-2- chloroacetamide 101-102 4 ##STR8## N(2-ethoxyphenyl- methyl)-2- chloroacetamide 56-59 5 ##STR9## N(4-ethoxyphenyl- methyl)-2- chloroacetamide 107-110 6 ##STR10## N(4-propoxyphenyl- methyl)-2- chloroacetamide 109-110 7 ##STR11## N(4-isopropoxyphenyl- methyl)-2- chloroacetami de 62-64 8 ##STR12## N(4-allyloxyphenyl- methyl)-2- chloroacetamide 109-111 __________________________________________________________________________
In the cases where the compound represented by the formula (I) according to this invention may be used as a herbicidal chemical, the compound is used singly or after diluting with a diluent in the same manner as in a conventional agricultural chemical to a suitable concentration applied by scattering or spraying, and if necessary, after addition of a suitable adjuvant such as a spreading agent, a wetting agent, a sticking agent, etc. to the compound, the mixture thus obtained is naturally applied.
In addition, in the cases where the decomposition of the compound is not considered after admixing with other physiologically active chemical and there is no fear of decomposing or degrading the admixed compound, there is an advantage of combination with the other physiologically active chemicals, for instance, herbicides, plant growth regulators, fungicides, bactericides, insecticides, etc. or with fertilizers, combination meaning the parallel application and the use as a mixture with such chemicals.